must concern
Verbo regular: concern - concerned- concerned

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must concern
you must concern
she must concern
we must concern
you must concern
they must concern 	I must be concerning
you must be concerning
she must be concerning
we must be concerning
you must be concerning
they must be concerning	I must have concerned
you must have concerned
she must have concerned
we must have concerned
you must have concerned
they must have concerned	I must have been concerning
you must have been concerning
she must have been concerning
we must have been concerning
you must have been concerning
they must have been concerning	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I mustn't concern
you mustn't concern
she mustn't concern
we mustn't concern
you mustn't concern
they mustn't concern 	I mustn't be concerning
you mustn't be concerning
she mustn't be concerning
we mustn't be concerning
you mustn't be concerning
they mustn't be concerning	I mustn't have concerned
you mustn't have concerned
she mustn't have concerned
we mustn't have concerned
you mustn't have concerned
they mustn't have concerned	I mustn't have been concerning
you mustn't have been concerning
she mustn't have been concerning
we mustn't have been concerning
you mustn't have been concerning
they mustn't have been concerning	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I concern?
must you concern?
must she concern?
must we concern?
must you concern?
must they concern? 	must I be concerning?
must you be concerning?
must she be concerning?
must we be concerning?
must you be concerning?
must they be concerning? 	must I have concerned?
must you have concerned?
must she have concerned?
must we have concerned?
must you have concerned?
must they have concerned? 	must I have been concerning?
must you have been concerning?
must she have been concerning?
must we have been concerning?
must you have been concerning?
must they have been concerning? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
mustn't I concern?
mustn't you concern?
mustn't she concern?
mustn't we concern?
mustn't you concern?
mustn't they concern? 	mustn't I be concerning?
mustn't you be concerning?
mustn't she be concerning?
mustn't we be concerning?
mustn't you be concerning?
mustn't they be concerning? 	mustn't I have concerned?
mustn't you have concerned?
mustn't she have concerned?
mustn't we have concerned?
mustn't you have concerned?
mustn't they have concerned? 	mustn't I have been concerning?
mustn't you have been concerning?
mustn't she have been concerning?
mustn't we have been concerning?
mustn't you have been concerning?
mustn't they have been concerning?